Bonded pack matrix with seals



July 22, 1969 J. P. HART ET AL.

BONDED PACK MATRIX WITH SEALS Filed March l1, 1968 3,456,717 Patented July 22, 1969 3,456,717 BONDED PACK MATRIX WITH SEALS .l ack P. Hart and James W. Tharp, Hinsdale, Ill., asslgnors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Mar. 11, 1968, Ser. No. 711,931

Int. Cl. F2Sd 17/ 04 U.S. Cl. 165-9 7 Claims ABSTRACT F THE DISCLOSURE A radial fiow regenerator matrix has a frame made up of two coaxial rims and a number of stitfeners extending from rim to rim. A number of shim packs extend from rim to rim, filling the space between adjacent stiffeners. The shim packs are made of corrugated thin metal sheets bonded together. They are embossed or compressed so as to define spaces for clearance from sealing means which cooperates with fixed seals in the regenerator, this sealing means being attached to the rims. Also, flat folded sheet metal tubes are disposed in the embossment to further insure against any compression of the shim packs against the sealing means.

Our invention relates to rotary regenerator matrices and particularly to improvements in radial flow regenerator matrices generally of the type described in U.S. Patent No. 3,368,613 of Addie and Hart for Rotary Regenerator Matrix Seal With Tensioning Means.

The matrix of the prior application comprises two rims, a number of stiffeners spaced around the rims and extending from rim to rim, foraminous heat transfer material filling the spaces between the rims and between adjacent stiffeners, and numerous labyrinth sealing means spaced circumferentially of the matrix located between short circumferential sections of the heat transfer material. The heat transfer material is defined by zigzag corrugated metal sheets stacked in tight contact.

To seal against the usual main seals of the regenerator, the matrix of the prior application includes sealing means defined by a sealing strip extending across the outer face of the matrix, a second sealing strip at the inner face of the matrix, and a number of struts connecting the two strips. To leave the sealing means free from compression by the matrix so that it would not be distorted by distortion of the matrix, the prior matrix structure includes spacers in the form of tapered plates with bosses on them abutting between the struts, thus defining a clearance for the sealing strips and struts.

The principal feature of our matrix is a modification of the structure described above to eliminate the spacer plates and thus increase the total porous area of the matrix and thereby improve its heat transfer characteristics; also, to bond the stack or pack of heat transfer sheets between adjacent sealing means into a unitary structure. Thus, the matrix according to our invention has the heat exchange structure defined by a stack of packs between adjacent stiffeners, each pack comprising a number of sheets bonded together. The bonded pack of sheets is embossed to define clearance for the sealing means or, to put it differently, to define bosses extending from the sides of the shim pack which abut similar bosses on adjacent shim packs defining a clearance adjacent the inner and outer faces of the matrix and where the struts extend through the matrix between the bosses. A further feature of our matrix is that the shim pack is compressed during the embossing process to have a convergence fitting the arc it fills in the matrix. Thus, the necessary taper from inner to outer faces of the matrix is taken up by this convergence of the individual shim packs.

A further desirable feature of the matrix lies in more deeply embossing the sides of the shim packs to provide pockets in which are received fiat tubes folded from sheet metal which additionally serve to prevent any binding contact between the shim packs and the struts.

The principal objects of our invention are to improve the endurance and efiiciency of regenerative matrices, and to reduce the cost and facilitate the assembly of such matrices.

The nature of our invention and the advantages thereof will be clear to those skilled in the art from the succeeding detailed description of the preferred embodiment of the invention and the accompanying drawings thereof.

FIGURE 1 is a schematic representation of a rotary regenerator illustrating the normal environment of our invention.

FIGURE 2 is a partial sectional view of the matrix, taken on a plane perpendicular to the axis thereof.

FIGURE 3 is an enlarged fragmentary view corresponding to FIGURE 2, with the individual metal sheets greatly exaggerated in thickness and the number of sheets per stack reduced, for clarity of illustration.

FIGURE 4 is a partial sectional view of the matrix taken on a plane containing the axis thereof as indicated by the line 4 4 in FIGURE 1, with parts broken away.

FIGURE 5 is a fragmentary sectional View taken in the plane indicated by the line 5-5 in FIGURE 3, embodying the same approach to depiction.

Referring first to FIGURE l, a typical regenerator of the sort to which our invention is preferably applied is shown somewhat schematically. It includes a housing 9 divided by a bulkhead 10 into two chambers and an annular drum-shaped matrix 11 mounted for rotation about an axis 13 so that it passes through the bulkhead at two points and moves through the chambers on either side of it. Main seals 14 are provided to minimize leakage where the matrix passes through the bulkhead. A first fluid, which may be air compressed by a compressor, enters the housing at the left as shown into a cool air space 15 from which it flows radially through the matrix and out a hot air outlet 17. A second fluid, which may be turbine exhaust gas, enters the space at the other side of the bulkhead through a hot gas entrance 18 and flows outwardly through the matrix into a space 19 which may be termed the exhaust space. Directions of flow may, of course, be changed, but this is the usual direction in installations of the sort for which our invention is intended. A problem in such installations lies in providing effective sealing at the main seals 14 notwithstanding the thermal deformation of the matrix. For this reason, the matrix includes labyrinth sealing strips which do not distort with the body of the matrix and thus maintain closer clearance with the main sea-ls.

Now referring also to FIGURES 2 and 4, the matrix includes two coaxial rims 21, one at each end of the matrix, these -being rigidly connected by a number of stiffeners 22 extending between the rims. In a particular embodiment of the invention there are twenty-five stiffeners. The spaces between the stiffeners are filled by heat transfer material in the form of a number of shim packs 23 (fifteen for each stiffener in the structure disclosed) and labyrinth seal means 25 extending from the inner and outer faces of the matrix between the shim packs, as well as additional labyrinth seal means 26 at each side of each stiffener. The labyrinth seal means may be the same or essentially the same as those described in the above-mentioned patent application No. 653,288. As shown particularly in FIGURE 4, a seal means 25 comprises a first sealing strip 27 extending across the outer face of the matrix from rim to rim, a second sealing strip 2-8 extending across the innerface of the matrix the inner face 33 of the heat transfer material 23. The

heat transfer material is in the form of packs of corrugated thin sheet metal (shim stock), ordinarily stainless steel, the preferred configuration of the corrugated sheet 34 'being indicated in FIGURE 4. These sheets have zigzag corrugations generally of the type described in United States Patent No. 3,183,963 of Mondt issued May 1 8, 1965. Specifically, in the described embodiment, the sheets 34 are of 0.002 inch stock bearing corrugations 40.019 inch high. Each shim pack 23 preferably is made up of a considerable number (twenty-eight in the specific structure described) of such corrugated sheets. Preferably, a flat or non-corrugated sheet 35 overlies each side, or radial surface, of the shim pack. Sheets 35 are a bit heavier, 0.005 inch in the specific example. This structure is illustrated in FIGURES 3 and 5 in which, however, the thickness of the elements is magnified for visual presentation and the number of sheets is correspondingly less than the preferred number in such an installation.

Thus, each shim pack 23 comprises a considerable number of corrugaed sheets 34 and two side sheets 35. These sheets are provided with tongues 37 which extend into a circumferential recess in the inner face of each rim 21. The sheets 34 and 35 are laid up in a suitable aligning fixture and diffusion bonded together to` form a unitary assembly of each shim pack. Following the bonding, the shim packs are squeezed between suitable dies in a press to impart a slight taper from the outer to the inner face and to emboss the sides to provide clearance for the seal means, as will be described later.

One edge of the circumferential groove in the rim is defined by an arcuate retainer assembly 38 on the inner face of the rim extending from one stiffener to the next, the retainer assemblies being fixed to the stiffener by cap screws 39. Retainer assemblies 38 also are coupled to tongues 41 on the outer sealing strips 27 so as to put these in tension. This mounting for the seal means is described and claimed in the above-mentioned patent application No. 653,288. For proper operation of the sealing means, it is essential that it not be caught or compressed between the shim packs so that it is constrained to distort along with the shim pack when the latter distorst because of the thermal gradient in it. For this reason, the edges or fiat faces of the shim packs which abut when the matrix is assembled are embossed to provide a surface which is relieved in the area of the sealing means; that is, the sealing strips 27 and 28 and struts 29. Or, to express it differently, each shim pack is embossed to provide rectangular bosses 42 which project through the rectangular openings 43 in the sealing means.

reduce'ai'r flowV through-the tubes 49 by-passing the heat exchange material, the walls of the tube are formed with suitable protuberances such as those indicated at 53 in FIGURE 3 reducing the clearance from the strut. Such protuberances, which may be simply embossment on the tube or any other suitable structure, approach the strut 29, but leave some clearance from it.

The seals 26 immediately adjacent the stiffeners 22 preferably follow the structure described in prior patent application No. 653,288, with fiat sheet metal spacers one of which has bosses on it to provide the clearance for the seal means. However, the structure at this point v may be simplified and less expensive Ibecause the spacers With these bosses 42 in abutment, the abutting shim packs define clearances 45 (FIGURE 3) for sealing strip 27, clearances 46 on both sides of the inner sealing strips 28, and a radial groove or trench'47 which provides clearance axially and circumferentially of the matrix from the strut 29. 'i

In the use of our invention, still further means may be provided if found to be needed to assure clearance for the struts, and this may be done with very simple structure. Flat tubes 49 folded from sheet metal are closed around the'struts 29. As 4will be apparent particularly from FIGURE 5, these tubes are simply a rebent metal sheetwith a flange 50 at one edge which completes the tubular enclosure. The stock for these tubes is much thicker than the heat exchange material-about 0.030 inch in the example described. To provide space for the tubes 49, the shim pack is embossed more deeply in the area occupied by these tubes to provide pockets 51. To

need not be tapered as in the structure of the prior application, since the convergence from outer to inner diameter is accommodated in the taper of the shim packs.

The embossment of the shim packs to clear the seal means may, of course, be employed with other configurations of the seal means than the described herein.

As will be clear, the present structure is almost entirely shim packs, and because of the elimination of a considerable number of the relatively thick metal spacers of the prior art, the overall effectiveness of the regenerator is increased. Because the shims, which are rather thin metal, are bonded together, the shim structure is not subject to vibration and fatigue due to the changes in pressure as it moves through the main seals. The integrated structure of the shim pack eliminates flutter of the shims. Thus, it will be clear to those skilled in the art that the structure herein described provides a substantial improvement in practical structures for regenerator applications.

The detailed description of preferred embodiments of our invention for the purpose of explaining the principles thereof is not to be considered as limiting the invention, since many modifications may be made by the exercise of skill in the art.

We claim:

1. A rotary regenerator matrix comprising, in combination, two spaced coaxial rims; stitfeners structurally connecting and spacing the rims; foraminous heat transfer structure having two faces and extending from one rim to the other open to tiow of fluid through the space between the rims from face to face of the heat transfer structure; labyrinth seal means extending across the heat transfer structure from rim to rim and extending outward from the faces of the heat transfer structure adapted to cooperate with sealing means disposed adjacent the matrix, each seal means comprising a first sealing strip extending across one face of the matrix, a second sealing strip extending across the other face of the matrix, and strut means distributed along the span of the said strips interconnecting the first and second strips so as to maintain a constant distance between the strips at the strut means; the foraminous heat transfer structure comprising a plural number of shim packs between each two adjacent stiffeners, the shim packs having mutually abutting sides extending from rim to rim and from face to face of the matrix, each shim pack comprising a plural number of thin sheets bonded together :to form a unitary mass, the sheets being configured to define passages between them from face to face of the matrix, the shim packs being formed to define relieved areas at the sides for clearance from the sealing strips and strut means when the sides of the packs are abutted so that the seal means are not clamped between the shim packs.

2. A regenerator matrix as defined in claim 1 in which the shim packs are formed with sides converging so as to form an arcuate stack when abutted.

3. A regenerator matrix as defined in claim 1 in which the .relieved areas adjacent the struts are relieved below those adjacent the sealing strips A.to define pockets, and including flat tubes enclosing the strut means with clearancemounted in the said pockets and bearing against the shim packs.

4. A regenerator matrix as deined in claim 3 in which the shim packs are formed with sides converging so as to form an arcuate stack when abutted.

5. A regenerator matrix as defined in claim 3 in which the tubes have a section of reduced clearance from the struts.

6. A regenerator matrix as defined in claim 5 in which the said section is an embossment of the tube.

7. A regenerator matrix as dened in claim 1 in which eac-h shim pack comprises a plural number of corrugated Sheets and a at cover sheet at each side of the pack.

6 References Cited UNITED STATES PATENTS 3,216,487 11/ 1965 Gallagher 165--9 3,367,405 2/ 1968 Addie et al. 16'5-9 ROBERT A. OLEARY, Primary Examiner ALBERT W. DAVIS, Assistant Examiner U.S. Cl. X.R. 

